Comparison of thresholding techniques for quantifying portland cement hydrates using synchrotron microtomography. (10th January 2021) - Deboodt, Tyler
Highlights: X-ray CT can be used to quantify synthesized hydration products. Multiple segmentation algorithms investigated for image volume processing. Pre-processing affects ability to segment. Local-segmentation provided improved results compared to global segmentation. Abstract: X-ray computed tomography (CT) has become increasingly popular for non-destructive investigation of cementitious systems. Differentiating solid phases in the reconstructed image volume has been reported as a challenge due to similar greyscale values, thus limiting x-ray CT to qualitative or semi-quantitative analysis for solid phases. The goal of this research was to investigate image preprocessing and segmentation algorithms in quantifying synthesized hydration products. C-S-H, calcium hydroxide, monosulfate, and ettringite were created in the laboratory for investigation. In this research, two local segmentation algorithms, Markov random fields and watershed, and one global segmentation algorithm, Gaussian histogram deconstruction, were studied for their ability to quantify the phases. It was found that misclassification of voxels occurred when using the Gaussian deconstruction. An average reduction of 50%, and as high as 180%, in the quantification errors were observed when using local segmentation algorithms.